Aqueous fuel cell system component ink compositions and methods of forming fuel cell system components using the same

ABSTRACT

A method of forming a fuel cell system component includes dispensing an ink onto a substrate to form an ink layer, the ink containing a fuel cell system component powder, an aqueous carrier, and an emulsion comprising a water-insoluble binder and a water soluble co-solvent, and solidifying the ink layer to form the fuel cell system component.

The present disclosure is directed generally to ink compositions andmore specifically to ink compositions used to form fuel cell systemcomponents.

BACKGROUND

Components of fuel cell systems may be formed by applying correspondingcomponent inks. However, conventional component inks may utilizehazardous solvents and/or may become unstable over time.

SUMMARY

According to various embodiments, a fuel cell system component inkcomprises a fuel cell system component powder, an aqueous carrier, andan emulsion comprising a water-insoluble binder and a water solubleco-solvent.

According to various embodiments, a method of forming a fuel cell systemcomponent includes dispensing an ink onto a substrate to form an inklayer, the ink containing a fuel cell system component powder, anaqueous carrier, and an emulsion comprising a water-insoluble binder anda water soluble co-solvent, and solidifying the ink layer to form thefuel cell system component.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of a SOFC stack, according to variousembodiments of the present disclosure.

FIG. 1B is a cross-sectional view of a portion of the stack of FIG. 1A.

FIG. 2A is a plan view of an air side of an interconnect, according tovarious embodiments of the present disclosure.

FIG. 2B is a plan view of a fuel side of the interconnect of FIG. 2A.

FIG. 3A is a plan view of an air side of a fuel cell, according tovarious embodiments of the present disclosure.

FIG. 3B is a plan view of a fuel side of the fuel cell of FIG. 3A.

FIG. 4 is a perspective view of a fuel cell according to variousembodiments of the present disclosure.

FIG. 5 is a cross-sectional view of a fuel cell stack according tovarious embodiments of the present disclosure.

DETAILED DESCRIPTION

The various embodiments will be described in detail with reference tothe accompanying drawings. Wherever possible, the same reference numberswill be used throughout the drawings to refer to the same or like parts.References made to particular examples and implementations are forillustrative purposes, and are not intended to limit the scope of theinvention or the claims.

It will be understood that when an element or layer is referred to asbeing “on” or “connected to” another element or layer, it can bedirectly on or directly connected to the other element or layer, orintervening elements or layers may be present. In contrast, when anelement is referred to as being “directly on” or “directly connected to”another element or layer, there are no intervening elements or layerspresent. It will be understood that for the purposes of this disclosure,“at least one of X, Y, and Z” can be construed as X only, Y only, Zonly, or any combination of two or more items X, Y, and Z (e.g., XYZ,XYY, YZ, ZZ).

Where a range of values is provided, it is understood that eachintervening value, to the tenth of the unit of the lower limit unlessthe context clearly dictates otherwise, between the upper and lowerlimit of that range and any other stated or intervening value in thatstated range is encompassed within the invention. The upper and lowerlimits of these smaller ranges may independently be included in thesmaller ranges is also encompassed within the invention, subject to anyspecifically excluded limit in the stated range. Where the stated rangeincludes one or both of the limits, ranges excluding either or both ofthose included limits are also included in the invention. It will alsobe understood that the term “about” may refer to a minor measurementerrors of, for example, 5 to 10%. In addition, weight percentages (wt %)and atomic percentages (at %) as used herein respectively refer to apercent of total weight or a percent of a total number of atoms of acorresponding composition.

Words such as “thereafter,” “then,” “next,” etc. are not necessarilyintended to limit the order of the steps; these words may be used toguide the reader through the description of the methods. Further, anyreference to claim elements in the singular, for example, using thearticles “a,” “an” or “the” is not to be construed as limiting theelement to the singular.

The term “fuel cell stack,” as used herein, means a plurality of stackedfuel cells that can optionally share a common fuel inlet and exhaustpassages or risers. The “fuel cell stack,” as used herein, includes adistinct electrical entity which contains two end plates which areconnected directly to power conditioning equipment and the power (i.e.,electricity) output of the stack or comprises a portion of a fuel cellcolumn that contains terminal plates which provide electrical output.

FIG. 1A is a perspective view of a fuel cell stack 100, and FIG. 1B is asectional view of a portion of the stack 100, according to variousembodiments of the present disclosure. Referring to FIGS. 1A and 1B, thestack 100 may be a solid oxide fuel cell (SOFC) stack that includes fuelcells 1 separated by interconnects 10. Referring to FIG. 1B, each fuelcell 1 comprises a cathode 3, a solid oxide electrolyte 5, and an anode7.

Various materials may be used for the cathode 3, electrolyte 5, andanode 7. For example, the anode 7 may comprise a cermet layer comprisinga metal-containing phase and a ceramic phase. The metal-containing phasemay include a metal catalyst, such as nickel (Ni), cobalt (Co), copper(Cu), alloys thereof, or the like, which operates as an electronconductor. The metal catalyst may be in a metallic state or may be in anoxide state. For example, the metal catalyst forms a metal oxide when itis in an oxidized state. Thus, the anode 7 may be annealed in a reducingatmosphere prior to operation of the fuel cell 1, to reduce the oxidizedmetal catalyst to a metallic state.

The metal-containing phase may consist entirely of nickel in a reducedstate. This nickel-containing phase may form nickel oxide when it is inan oxidized state. Thus, the anode 7 is preferably annealed in areducing atmosphere prior to operation to reduce the nickel oxide tonickel.

According to some embodiments, the metallic phase may include the metalcatalyst and a dopant. For example, the metallic phase may berepresented by Formula 1: [D_(x)M_(1-x)]_(y)O. In Formula 1, D is adopant (in any oxidation state) selected from magnesium (Mg), calcium(Ca), titanium (Ti), aluminum (Al), manganese (Mn), tungsten (W),niobium (Nb), chromium (Cr), iron (Fe), vanadium (V), praseodymium (Pr),cerium (Ce), zirconium (Zr) or the like, or any combination thereof. Insome embodiments, D may be Ca, Mg, and/or Ti. M is a metal catalystselected from nickel (Ni), cobalt (Co), copper (Cu), or alloys thereof.X may range from about 0.01 to about 0.1, and y may range from about 1to about 2. In other embodiments, x may range from about 0.01 to about0.04. For example, x may be about 0.02 and y may be either 1 or 2.

Accordingly, the metallic phase may comprise from about 1 to about 10atomic percent (“at %”) of the metal oxide dopant and about 99 to about90 at % of the metal catalyst. For example, the metallic phase maycomprise from about 2 to about 4 at % of the metal oxide dopant andabout 98 to about 96 at % of the metal catalyst, as manufactured beforebeing reduced.

According to various embodiments, the anode 7 may include a metallicphase that includes NiO doped with MgO. For example, the metallic phasemay include Mg_(x)Ni_(1-x)O, wherein x is within the ranges describedabove. After anode manufacture and before or during fuel cell operation,the metallic phase is reduced by being exposed to a reducing ambient(e.g., fuel) at an elevated temperature (e.g., at a temperature rangingfrom about 750-950° C.). The reduced metallic phase may be representedby the formula D_(x)M_(1-x).

The ceramic phase of the anode 7 may include, but is not limited togadolinia-doped ceria (GDC), samaria-doped ceria (SDC), ytterbia-dopedceria (YDC), scandia-stabilized zirconia (SSZ),ytterbia-ceria-scandia-stabilized zirconia (YCSSZ), or the like. In theYCSSZ, scandia may be present in an amount equal to 9 to 11 mol %, suchas 10 mol %, ceria may present in amount greater than 0 (e.g., at least0.5 mol %) and equal to or less than 2.5 mol %, such as 1 mol %, and atleast one of yttria and ytterbia may be present in an amount greaterthan 0 and equal to or less than 2.5 mol %, such as 1 mol %, asdisclosed in U.S. Pat. No. 8,580,456, which is incorporated herein, byreference. Yttria stabilized zirconia (YSZ) may be excluded from theceramic phase of the anode 7.

The electrolyte 5 may comprise a stabilized zirconia, such asscandia-stabilized zirconia (SSZ), yttria-stabilized zirconia (YSZ),scandia-ceria-stabilized zirconia (SCSZ),scandia-ceria-yttria-stabilized zirconia (SCYSZ), or the like.Alternatively, the electrolyte 5 may comprise another ionicallyconductive material, such as a samaria-doped ceria (SDC),gadolinia-doped ceria (GDC), or yttria-doped ceria (YDC).

The cathode 3 may comprise a layer of an electrically conductivematerial, such as an electrically conductive perovskite material, suchas lanthanum strontium manganite (LSM). Other conductive perovskites,such as lanthanum strontium cobaltite (LSC), lanthanum strontium cobaltmanganite (LSCM), lanthanum strontium cobalt ferrite (LSCF), lanthanumstrontium ferrite (LSF). La_(0.85)Sr_(0.15)Cr_(0.9)Ni_(0.1)O₃ (LSCN),etc., or metals, such as Pt, may also be used.

The cathode 3 may optionally contain a ceramic phase similar to theanode 7. The electrodes and the electrolyte may each comprise one ormore sublayers of one or more of the above described materials. Thus, insome embodiments, the cathode 3 may comprise a mixture of theelectrically conductive material and an ionically conductive material.For example, the cathode 3 may include from about 10 wt % to about 90 wt% of the electrically conductive material described above, (e.g., LSM,etc.) and from about 10 wt % to about 90 wt % of the ionicallyconductive material. Suitable ionically conductive materials includezirconia-based and/or ceria based materials. For example, the ionicallyconductive material may comprise scandia-stabilized zirconia (SSZ),ceria, and at least one of yttria and ytterbia. In some embodiments, theionically conductive material may be represented by the formula:(ZrO₂)_(1-w-x-z)(Sc₂O₃)_(w)(CeO₂)_(x)(Y₂O₃)_(a)(Yb₂O₃)_(b), wherein0.09≤w≤0.11, 0<x≤0.0125, a+b=z, and 0.0025≤z≤0.0125. In someembodiments, 0.009<x≤0.011 and 0.009≤z≤0.011, and optionally either a orb may equal to zero if the other one of a or b does not equal to zero.

Furthermore, if desired, additional contact or current collector layersmay be placed over the cathode 3 and anode 7, while additionalinterfacial layers, such as doped ceria interfacial layers, may belocated between the electrodes 3, 7 and the electrolyte 5. For example,a Ni or nickel oxide anode contact layer and an LSM or LSCo cathodecontact layer may be formed on the anode 7 and cathode 3 electrodes,respectively.

Fuel cell stacks are frequently built from a multiplicity of fuel cells1 in the form of planar elements, tubes, or other geometries. Althoughthe fuel cell stack 100 in FIG. 1 is vertically oriented, fuel cellstacks may be oriented horizontally or in any other direction. Fuel andair may be provided to the electrochemically active surface, which canbe large. For example, fuel may be provided through fuel conduits 22(e.g., fuel riser openings) formed in each interconnect 10 and fuel cell1, while air may be provided from the side of the stack between air sideribs of the interconnects 10.

Each interconnect 10 electrically connects adjacent fuel cells 1 in thestack 100. In particular, an interconnect 10 may electrically connectthe anode 7 of one fuel cell 1 to the cathode 3 of an adjacent fuel cell1. FIG. 1B shows that the lower fuel cell 1 is located between twointerconnects 10. A Ni mesh (not shown) may be used to electricallyconnect the interconnect 10 to the anode 7 of an adjacent fuel cell 1.

Each interconnect 10 includes fuel-side ribs 12A that at least partiallydefine fuel channels 8A and air-side ribs 12B that at least partiallydefine oxidant (e.g., air) channels 8B. The interconnect 10 may operateas a gas-fuel separator that separates a fuel, such as a hydrocarbonfuel, flowing to the fuel electrode (i.e. anode 7) of one cell in thestack from oxidant, such as air, flowing to the air electrode (i.e.cathode 3) of an adjacent cell in the stack. At either end of the stack100, there may be an air end plate or fuel end plate (not shown) forproviding air or fuel, respectively, to the end electrode.

Each interconnect 10 may be made of or may contain electricallyconductive material, such as a metal alloy (e.g., chromium-iron alloy)which has a similar coefficient of thermal expansion to that of thesolid oxide electrolyte in the cells (e.g., a difference of 0-10%). Forexample, the interconnects 10 may comprise a metal (e.g., achromium-iron alloy, such as 4-6 weight percent iron (e.g., 5 wt %iron), optionally 1 or less weight percent yttrium and balance chromiumalloy), and may electrically connect the anode or fuel-side of one fuelcell 1 to the cathode or air-side of an adjacent fuel cell 1. Anelectrically conductive contact layer, such as a nickel contact layer,may be provided between anodes 7 and each interconnect 10. Anotheroptional electrically conductive contact layer may be provided betweenthe cathodes 3 and each interconnect 10.

FIG. 2A is a top view of the air side of the interconnect 10, and FIG.2B is a top view of a fuel side of the interconnect 10, according tovarious embodiments of the present disclosure. Referring to FIGS. 1B and2A, the air side includes the air channels 8B that extend from opposingfirst and second edges 30, 32 of the interconnect 10. Air flows throughthe air channels 8B to a cathode 3 of an adjacent fuel cell 1. Ringseals 20 may surround fuel holes 22A, 22B of the interconnect 10, toprevent fuel from contacting the cathode. Strip-shaped peripheral seals24 are located on peripheral portions of the air side of theinterconnect 10. The seals 20, 24 may be formed of a glass orglass-ceramic material. The peripheral portions may be an elevatedplateau which does not include ribs or channels. The surface of theperipheral regions may be coplanar with tops of the ribs 12B.

Referring to FIGS. 1B and 2B, the fuel side of the interconnect 10 mayinclude the fuel channels 8A and fuel manifolds 28. Fuel flows from oneof the fuel holes 22A (e.g., inlet fuel hole that forms part of the fuelinlet riser), into the adjacent manifold 28, through the fuel channels8A, and to an anode 7 of an adjacent fuel cell 1. Excess fuel may flowinto the other fuel manifold 28 and then into the outlet fuel hole 22B.A frame seal 26 is disposed on a peripheral region of the fuel side ofthe interconnect 10. The peripheral region may be an elevated plateauwhich does not include ribs or channels. The surface of the peripheralregion may be coplanar with tops of the ribs 12A.

FIG. 3A is a plan view of a cathode side (e.g., air side) of the fuelcell 1, and FIG. 3B is a plan view of an anode side (e.g., fuel side) ofthe fuel cell 1, according to various embodiments of the presentdisclosure. Referring to FIGS. 1A, 2A, 3A, and 3B, the fuel cell 1 mayinclude an inlet fuel hole 22A, an outlet fuel hole 22B, the electrolyte5, and the cathode 3. The cathode 3 may be disposed on a first side ofthe electrolyte 5. The anode 7 may be disposed on an opposing secondside of the electrolyte 5. The fuel cell 1 may include a first edge 130and an opposing second edge 132 that correspond to the first and secondedges 30, 32 of the interconnect 10.

The fuel holes 22A, 22B may extend through the electrolyte 5 and may bearranged to overlap with the fuel holes 22A, 22B of the interconnects10, when assembled in the fuel cell stack 100. The cathode 3 may beprinted on the electrolyte 5 so as not to overlap with the ring seals 20and the peripheral seals 24 when assembled in the fuel cell stack 100.The anode 7 may have a similar shape as the cathode 3. The anode 7 maybe disposed so as not to overlap with the frame seal 26, when assembledin the stack 100. In other words, the cathode 3 and the anode 7 may berecessed from the edges of the electrolyte 5, such that correspondingedge regions of the electrolyte 5 may directly contact the correspondingseals 20, 24, 26.

FIG. 4 is a perspective view of a fuel cell 1 containing a strengthening(e.g., reinforcing) layer 40 according to various embodiments of thepresent disclosure. In addition to its strengthening properties, thislayer can also serve as a dielectric barrier. The strengthening layerstrengthens the area of the electrolyte 5 around the fuel holes 22A,22B. The strengthening layers 40 at least partially surround the fuelholes 22A, 22B, as described in U.S. Pat. No. 10,347,930 B2 which issuedon Jul. 9, 2019 and which is incorporated herein by reference in itsentirety. The strengthening layers 40 can be in the shape of asemicircle, horseshoe, crescent, or U-shaped. Preferably, thestrengthening layers 40 are formed on the anode 7 side of theelectrolyte 5 and do not form complete circles around the perimeters ofthe fuel holes 22A, 22B, but are partially open (e.g., contain achannel) to allow fuel from the anode side to enter and exit the fuelholes 22A, 22B. The strengthening layers can also run along theperimeter of the cell on either or both sides of the cell. Thestrengthening layers 40 may be formed of a ceramic material, such as astabilized zirconia, alumina or a combination thereof. For example, thestrengthening layers 40 may be formed of YSZ and alpha alumina.

FIG. 5 is a cross-sectional view of a fuel cell stack 100 containing acorrosion barrier layer 50 according to various embodiments of thepresent disclosure. The interconnects 10 contain a metal oxide coating11 (e.g., lanthanum strontium manganite (“LSM”) and/or manganese cobaltoxide (“MCO”) spinel coating) located on the air side (e.g., on the ribs12B and/or in channels 8B) of the interconnect 10. The corrosion barrierlayer 50 acts as a barrier to diffusion of at least one of manganese orcobalt from a metal oxide coating 11 into the ring seal 20.

The corrosion barrier layer 50 reduces or prevents the interaction ofthe components of the LSM and/or MCO coating with the silica based glassseals 20 and/or prevents the interaction of manganese contaminatedsilica based glass seals 20 with the electrolyte 5 of the fuel cell 1.Specifically, a barrier layer which preferably lacks any Mn and/or Co(or at least contains less than 5 at % of Mn and/or Co) prevents Mnand/or Co diffusion from the metal oxide layer into the glass sealand/or prevents the Mn and/or Co containing mobile phase diffusion fromthe glass seal to the electrolyte.

The corrosion barrier layer 50 may comprise a glass ceramic materialdescribed in U.S. Pat. No. 9,583,771 B2, issued Feb. 28, 2017 andincorporated herein by reference in its entirety. The corrosion barrierlayer 50 may comprise a glass ceramic layer formed from a substantiallyglass barrier precursor layer containing at least 90 wt. % glass (e.g.,90-100 wt. % glass, such as around 99 to 100 wt. % amorphous glass and 0to 1 wt. % crystalline phase) applied to a surface of interconnects inthe SOFC stack. In one embodiment, the glass barrier precursor layercontains at least 90 wt. % glass and comprises:

45-55 wt. % silica (SiO₂);

5-10 wt. % potassium oxide (K₂O);

2-5 wt. % calcium oxide (CaO);

2-5 wt. % barium oxide (BaO);

0-1 wt. % boron trioxide (B₂O₃);

15-25 wt. % alumina (Al₂O₃); and

20-30 wt. % zirconia (ZrO₂) on an oxide weight basis.

In one preferred embodiment, the glass barrier precursor layercomprises:

44.6 wt. % silica;

6.3 wt. % potassium oxide;

2.4 wt. % calcium oxide;

2.4 wt. % barium oxide;

19.1 wt. % alumina;

0.1 wt. % boron trioxide; and

25.1 wt. % zirconia on an oxide weight basis.

Fuel Cell System Component Inks

In various embodiments, the fuel cell system component inks may be usedto form various components of a fuel cell system, such as a solid oxidefuel cell stack 100. For example, the fuel cell system component inksmay be used to form fuel cell 1 cathodes 3, anodes 7, fuel-side and/orair-side seals 20, 24, 26, strengthening layers 40, corrosion barrierlayers 50, other fuel cell system dielectric layers, or the like. Thefuel cell system component inks may be deposited on a substrate, such asa fuel cell 1 or interconnect 10, using any suitable deposition method.For example, the fuel cell system component inks may be configured to bedeposited by screen printing, inkjet printing, dip coating, spraycoating, or the like.

The fuel cell system component inks may include a fuel cell systemcomponent powder, an aqueous carrier, and a water-insoluble binder in anemulsion. The emulsion may comprise the water-insoluble binder dissolvedin a water soluble co-solvent. The water-insoluble binder may comprise acellulosic binder, such as ethyl cellulose. The water soluble co-solventmay comprise any solvent that is sufficiently soluble in water, such asterpineol.

In contrast, conventional inks that include aqueous carriers typicallyinclude binders that are water-soluble. However, the conventional inkformulations incorporating water-soluble binders are more sensitive tohumidity shifts than the emulsion binder compositions of the embodimentsof the present disclosure. By maintaining an emulsion of thewater-insoluble binder in a co-solvent in the aqueous medium (i.e., in awater solvent), the embodiment fuel cell system component inks retainrobustness when encountering humidity changes and retain the benefits ofan aqueous-based system, such as environmental compliance, safety, etc.

The fuel cell system component inks described herein may include acomponent powder and an emulsion comprising water-insoluble binder in awater soluble co-solvent in a in an aqueous carrier. The aqueous carriermay comprise water as the primary solvent, and one or more binders,dispersants, plasticizers, and/or anti-abrasion components. In someembodiments, the fuel cell system component ink may optionally comprisean additive selected from, dispersants, thickening agents,deflocculants, anti-settling agents, anti-foaming agents, anti-microbialagents, emollients, surfactants, lubricants, or any combination thereof.

The component powder may comprise an electrically conductive material,an ionically conductive material, a corrosion barrier material, a sealmaterial, a strengthening material, and/or a dielectric material (e.g.,dielectric barrier material).

According to various embodiments of the present disclosure, an amount ofcomponent powder included in the fuel cell system component ink may varydepending on the particle size of the component powder and an associatedsurface area. For example, the fuel cell system component ink mayinclude from about 50 wt % to about 90 wt %, such as from about 58 wt %to about 85 wt %, or from about 62 wt % to about 80 wt %, componentpowder.

In various embodiments, the fuel cell system component ink may includefrom about 5 wt % to about 21 wt %, such as from about 7 wt % to about19 wt %, or from about 8 wt % to about 18 wt % aqueous carrier. Forexample, the aqueous carrier may include distilled or deionized water.

In various embodiments, the fuel cell system component ink may includefrom about 0.2 wt % to about 10 wt %, such as from about 0.4 to about 8wt %, or from about 0.5 to about 6 wt %, water-insoluble binder. Thebinder may include any suitable water-insoluble binder or bindermixture. For example, suitable binders may include cellulosic binders,such as ethyl cellulose binders, or acrylic resin binders, such asthermoplastic high molecular weight n-butyl methacrylate polymers (e.g.,Elvacite 2044), high molecular weight iso-butyl methacrylate polymers(e.g., Elvacite 2045), methyl methacrylate copolymers (e.g., Elvacite2669), or any combinations thereof.

The fuel cell system component ink may include from about 0.2 wt % toabout 12 wt %, such as from about 0.3 wt % to about 10 wt %, includingfrom about 0.5 wt % to about 8 wt %, plasticizer. The plasticizer mayinclude any suitable plasticizer or plasticizer mixture. For example,usable plasticizers include phthalates, such as benzyl butyl phthalate(BBP) or dibutyl phthalate (DBP), diols such as polyethylene glycol(PEG), or the like, or any combinations thereof. In some embodiments,the plasticizer may have a MW ranging from about 100 to about 5,000g/mol, such as from about 200 to about 4,000 g/mol. In preferredembodiments, the plasticizer may be PEG-400, which may have a molar massof 380-420 g/mol.

In some embodiments, the fuel cell system component ink may include fromabout 0.2 wt % to about 10 wt %, such as from about 0.4 to about 8 wt %,or from about 0.5 to about 6 wt %, dispersant. The dispersant mayinclude any suitable water-insoluble dispersant or dispersant mixture.For example, suitable dispersants include polymeric alkoxylatedispersants, ionic polymeric dispersants, or the like. For example,particular dispersants include polymeric and monomeric dispersants,which may be cationic or anionic and may be used alone or incombination. For example, suitable dispersants include Hypermer KD2,KD4, KD15, and KD21 dispersants available from Croda Advanced Materials,and Solsperse 24000 and 26000 dispersants available from Lubrizol Corp,for example.

In some embodiments, the fuel cell system component ink may include fromabout 0.2 wt % to about 10 wt %, such as from about 0.4 to about 8 wt %,or from about 0.5 to about 6 wt %, co-solvent. The co-solvent mayinclude any suitable water soluble co-solvent or co-solvent mixturesuitable for solubilizing the binder. For example, suitable co-solventsmay include terpineol, toluene, ester alcohol (such as Texanol esteralcohol available from the Eastman Co.), or the like.

In various embodiments, the fuel cell system component ink may includefrom about 62 wt % to about 80 wt % component powder, from about 8 wt %to about 18 wt % water, from about 0.5 wt % to about 8 wt % plasticizer,from about 0.5 wt % to about 6 wt % binder, from about 0.5 wt % to about6 wt % co-solvent, and from about 0.5 wt % to about 6 wt % dispersant.

According to various embodiments of the present disclosure, the fuelcell system component ink may be formulated as a cathode ink configuredto form a fuel cell cathode. In particular, the component powder of thecathode ink may be a cathode powder that may include an electricallyconducive ceramic material, an ionically conductive ceramic material, ora combination thereof. For example, suitable electronically conductiveceramic materials include LSM, LSCM, LSCF, LSC, LSF, LSCN, or the like,and suitable ionically conductive ceramic materials include YSZ, SSZ,SDC, GDC, or the like.

The cathode powder may be dispersed in a carrier as described above. Forexample, the cathode ink may include water and a plasticizer, binder,co-solvent, and dispersant, as described above, in amounts as describedabove.

According to various embodiments of the present disclosure, the fuelcell system component ink may be formulated as an anode ink configuredto form a fuel cell anode. In particular, the component powder of theanode ink may be an anode powder that may include an electricallyconductive metal oxide, and ionically conductive ceramic material, or acombination thereof. For example, the anode powder may comprise NiO/SDC,NiO/GDC, NiO/SSZ, or the like.

The anode powder may be dispersed in a carrier as described above. Forexample, the anode ink may include water and a plasticizer, binder,co-solvent, and dispersant, as described above, in amounts as describedabove.

According to various embodiments of the present disclosure, the fuelcell system component ink may be configured as a seal ink configured toform fuel cell seals. In particular, the component powder of the sealink may be a seal powder including a glass material, a glass-ceramicmaterial, or a combination thereof. For example, suitable seal powdersinclude silicate-based glass materials, zircon-based materials,mica-based materials, or the like.

The seal powder may be dispersed in a carrier as described above. Forexample, the seal ink may include water and a plasticizer, binder,co-solvent, and dispersant, as described above, in amounts as describedabove.

According to various embodiments of the present disclosure, the fuelcell system component ink may be formulated as an auxiliary layer inkconfigured to form auxiliary fuel cell layers, such as corrosion barrierlayers, strengthening layers, dielectric layers, etc. In particular, thecomponent powder of the auxiliary layer ink may be an auxiliary layerpowder that may include inert ceramic materials, such as alumina,zirconia, zircon, feldspar, silicate glass, or the like. For example,the component powder may be stabilized zirconia and/or alumina to formthe strengthening layers 40 on the electrolyte 5 of the fuel cells 1.Alternatively, the component powder may be glass or glass-ceramicprecursor powder described above to form the corrosion barrier layers 50over the metal oxide coating 11 on the air side of the interconnects 10.

The auxiliary layer powder may be dispersed in a carrier as describedabove. For example, the auxiliary layer ink may include water and aplasticizer, binder, co-solvent, and dispersant, as described above, inamounts as described above.

Fuel Cell System Component Manufacturing

Various embodiments of the present disclosure provide methods ofmanufacturing fuel cell system components by depositing fuel cell systemcomponent inks on a substrate. The fuel cell system component inks maybe deposited on a substrate using any suitable method, such as by screenprinting, inkjet printing, dip coating, spraying, or the like. Forexample, fuel cell system component inks may be used to form fuel cellcathodes, anodes, seals, barrier layers, strengthening layers,dielectric layers, corrosion barrier layers, or the like, and may bereferred to herein according to the component formed therefrom.

The deposited fuel cell system component ink may be dried in alow-temperature process to make the make the deposited layer more stableand/or abrasion resistant. For example, the deposited ink may be driedat a temperature of from about 80° C. to about 300° C., such as about120° C. to about 280° C. The dried ink layer may then be sintered in areducing or oxidizing atmosphere, in order to densify the layer.

For example, the fuel cell 1 of FIG. 1B may be manufactured bydepositing (e.g., printing) an anode ink on a first side of theelectrolyte 5 to, and by depositing a cathode ink on an opposing secondside of the electrolyte 5. The deposition may include screen printing,inkjet printing, dip coating, spray coating, or the like. In someembodiments, the anode and cathode inks may each be deposited in asingle deposition step and at a desired thickness. For example, theviscosity of the anode and/or cathode inks may be sufficiently lowenough to print an ink layer having a thickness ranging from about 2 μmto about 100 μm, in a single printing step, without degrading electricalperformance of the layer and/or without cracking or delamination of thelayer.

After deposition, the cathode and anode inks may be dried in a lowtemperature process to solidify the inks and form the anode 7 on thefirst side of the substrate and to form the cathode 3 on the second sideof the electrolyte 5. In particular, the drying may the make thedeposited ink layers more stable and/or abrasion resistant. For example,the cathode and anode inks may be dried at a temperature of from about80° C. to about 300° C., such as about 120° C. to about 280° C., tosolidify the cathode 3 and the anode 7. In some embodiments, one of thecathode or anode ink may be deposited and dried, and then the other ofthe cathode or anode ink may be deposited and dried. In otherembodiments, the anode and cathodes may both be deposited and then driedin a single step.

In some embodiments, the cathode 3 and anode 7 may then be separatelysintered in a controlled environment, such as in a reducing environment.However, in other embodiments, the cathode 3 and anode 7 may besimultaneously sintered in a single step.

Referring to FIGS. 2A and 2B, in some embodiments, a seal ink may bedeposited onto opposing sides on the interconnect 10, to form one ormore of the seals 20, 24, 26. The deposited seals 20, 24, 26 may beindividually or collectively dried using a low temperature process asdescribed above, in order to make the seals more stable and/or abrasionresistant. For example, the seal ink may be dried at a temperature offrom about 80° C. to about 300° C., such as about 120° C. to about 280°C., to solidify the seals 20, 24, 26.

The seals 20, 24, 26 may then be sintered at a temperature above theglass transition temperature of the seal material. For example, fuelcells 1 and interconnects 10 may be assembled together into a fuel cellstack 100, before or after sintering the cathodes and anodes. The stack100 may be heated to sinter at least the seals 20, 24, 26, if the anodesand cathodes were previously sintered, or to collectively sinter theseals 20, 24, 26, the cathodes 3, and the anodes 7, in a single step.For example, the sintering may include subjecting the stack 100 to areducing environment and temperatures ranging from about 700° C. toabout 1100° C.

In some embodiments, the method includes stacking one or more of thefuel cells between the interconnects to form a fuel cell stack, afterthe drying of the cathodes, anodes, and seals. The stack may then beheated to sinter the cathodes, anodes, and the seals in a single step.In other embodiments, the cathodes and/or anodes may be sintered beforethe assembly of the stack, and the heating may include sintering of theseals.

Although the foregoing refers to particular preferred embodiments, itwill be understood that the invention is not so limited. It will occurto those of ordinary skill in the art that various modifications may bemade to the disclosed embodiments and that such modifications areintended to be within the scope of the invention. All of thepublications, patent applications and patents cited herein areincorporated herein by reference in their entirety.

What is claimed is:
 1. A fuel cell system component ink, comprising: afuel cell system component powder, an aqueous carrier, and an emulsioncomprising a water-insoluble binder and a water soluble co-solvent. 2.The ink of claim 1, wherein the ink comprises, based on the total weightof the ink: from about 50 wt % to about 90 wt % of the fuel cell systemcomponent powder, from about 5 wt % to about 21 wt % of the aqueouscarrier; from about 0.2 wt % to about 10 wt % of the co-solvent; andfrom about 0.2 wt % to about 10 wt % of the water-insoluble binderemulsified in the co-solvent.
 3. The ink of claim 2, further comprisingfrom about 0.2 wt % to about 12 wt % of a plasticizer selected frombutyl phthalate (BBP), dibutyl phthalate (DBP), polyethylene glycol(PEG), or any combination thereof.
 4. The ink of claim 2, furthercomprising from about 0.2 wt % to about 10 wt % of a dispersant.
 5. Theink of claim 1, wherein the binder comprises a cellulosic binder.
 6. Theink of claim 5, wherein the binder comprises ethyl cellulose.
 7. The inkof claim 1, wherein the binder comprises an acrylic resin.
 8. The ink ofclaim 1, wherein the co-solvent comprises terpineol, toluene, an esteralcohol, or any combination thereof, and wherein the aqueous carriercomprises water.
 9. The ink of claim 1, wherein the fuel cell systemcomponent powder comprises a fuel cell anode material, a fuel cellcathode material, a fuel cell corrosion barrier layer material, aceramic dielectric barrier or strengthening layer material or a glass ora glass-ceramic fuel cell seal material.
 10. The ink of claim 2, whereinthe ink comprises: from about 62 wt % to about 80 wt % of the fuel cellsystem component powder; from about 8 wt % to about 10 wt % of theaqueous carrier, from about 0.5 wt % to about 6 wt % of thewater-insoluble binder; from about 0.5 wt % to about 8 wt % of aplasticizer, from about 0.5 wt % to about 6 wt % of a co-solventconfigured to solubilize the binder in the carrier; and from about 0.5wt % to about 6 wt % of a dispersant.
 11. A method of forming a fuelcell system component, comprising: dispensing an ink onto a substrate toform an ink layer, the ink comprising: a fuel cell system componentpowder; an aqueous carrier; and an emulsion comprising a water-insolublebinder and a water soluble co-solvent; and solidifying the ink layer toform the fuel cell system component.
 12. The method of claim 11,wherein: the solidifying the ink layer comprises drying and sinteringthe ink layer, and the ink comprises, based on the total weight of eachink: from about 50 wt % to about 90 wt % of the fuel cell systemcomponent powder, from about 5 wt % to about 21 wt % of the aqueouscarrier; from about 0.2 wt % to about 10 wt % of the co-solvent; andfrom about 0.2 wt % to about 10 wt % of the water-insoluble binderemulsified in the co-solvent.
 13. The method of claim 12, furthercomprising from about 0.2 wt % to about 12 wt % of a plasticizerselected from butyl phthalate (BBP), dibutyl phthalate (DBP),polyethylene glycol (PEG), or any combination thereof.
 14. The method ofclaim 12, further comprising from about 0.2 wt % to about 10 wt % of adispersant.
 15. The method of claim 11, wherein the binder comprises acellulosic binder.
 16. The method of claim 15, wherein the bindercomprises ethyl cellulose.
 17. The method of claim 11, wherein thebinder comprises an acrylic resin.
 18. The method of claim 11, whereinthe co-solvent comprises terpineol, toluene, an ester alcohol, or anycombination thereof, and wherein the aqueous carrier comprises water.19. The method of claim 11, wherein the fuel cell system componentpowder comprises a fuel cell anode material, a fuel cell cathodematerial, a fuel cell corrosion barrier layer material, a ceramicdielectric barrier or strengthening layer material or a glass or aglass-ceramic fuel cell seal material.
 20. The method of claim 12,wherein the ink comprises: from about 62 wt % to about 80 wt % of thefuel cell system component powder; from about 8 wt % to about 10 wt % ofthe aqueous carrier, from about 0.5 wt % to about 6 wt % of thewater-insoluble binder; from about 0.5 wt % to about 8 wt % of aplasticizer, from about 0.5 wt % to about 6 wt % of a co-solventconfigured to solubilize the binder in the carrier, and from about 0.5wt % to about 6 wt % of a dispersant.